I'm considering purchasing a 3DR Radio kit for a ground vehicle, which is the best option in this situation, 433mKz or 915mHz ? My understanding is that the 433mHz is probable the better option.
Also, I noticed that the 915mHz kit comes with an air and ground module where as the 433mHz has 2 air modules. Why is this and how can one of the air modues be converted to a ground module?
Replies
The whole air/ground module is the fact that these are modems and communicate on the wire side of the radio via TTL level serial (the same thing Arduino uses natively). The ground modules had an additional FTDI chip to convert the TTL to USB. On the 413mHz radios, they had an interference problem with a lot of USB chipsets and thus dropped the additional FTDI chip based ground module and just ship the air modem (TTL only) and you use your own TTL to USB cable (AKA FTDI cable). Logic applies here that the FTDI chip is now in the USB plug at the computer, some distance from the module and eliminates the noise problem.
What matters is what country you live in. The 915mHz is legal in the US and the 433mHz is legal in some other countries. That fact is actually covered on the page. Don't operate a radio that is not legal where you live.
DOCUMENTATION, SET UP AND COUNTRY COMPATIBILITY
Support for different countries/regions
It is very important that you find out what the local country or region regulations are on frequency, hopping channels and power levels and configure your 3DR Radios correctly for your local rules.
Here is some general information to help you get started.